Mammalian L1 retrotransposons as genetic characters

National Institute Of Diabetes And Digestive And Kidney Diseases

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Abstract

The original impetus for this project was that mammalian L1 elements are obligate intra-genomic parasites that replicate by copying their RNA transcripts into genomic DNA. They have been residing and evolving in mammalian lineages for at least the last 100 million years, during which time at least 16 successive L1 families arose, only to go extinct having been supplanted by a novel active family, which is present in modern humans. The DNA inserts of the extinct L1 families remain in the genome where they accumulate mutations at the neutral mutation rate. These insertions represent an unparalleled source of DNA fossils that provide a genetic record of its host and our analysis of which suggested that DNA repair may be mutagenic. We had earlier demonstrated that this is indeed the case and determined several mechanisms of repair-induced mutagenesis. However, as we devoted no resources this project in the current rating year we have nothin new to report.